Humanity's Strongest Nanny
by Canna
Summary: If anyone were to tell Levi that he would find a full-time career in baby-sitting some rich bastard's spoiled brat a year ago, he would shove a rifle up their ass and pull the trigger.
1. Prolouge (One-Shot)

**"AAAAH!"**

A sharp scream echoed into the air, drawing bystanders' eyes as everyone turned to the woman looking mortified with a young child in her arms.

"S-someone call the police!" The man next to her shouted. "Those kids were kidnapped!" He cried, pointing wildly at the black van going way past the speed limit.

The entire street burst into uproar as people scrambled for their phones. The responsible ones immediately dialled the numbers to call for help while others began taking videos and snap shots to send to their friends.

As onlookers watched the vehicle speed away in horror, the car began to shake. It wobbled from side to side, skiing dangerously across the lane before it suddenly turn made a sharp turn and smashed straight into a lamppost.

Silence filled the street as the citizens of Shiganshina stared in confusion. No one dared to approach the car, as no body want to confront kidnappers—and possibly armed ones too. There are a few people trying to get a glimpse through the tinted windows from the distance, but it was impossible to see the inside.

Murmurs began filled the street, only to be quickly silenced when the car shook.

It was then they heard faint screams coming from inside the car. The van shook once, then twice, and then…nothing.

A brave teen tried to walk up, ignoring the hisses and warnings from his friends as he crept closer. Then all of the sudden, the door opened. Or rather, it _flew_ open. The boy screamed, jumping back in shock as the door smashed into the ground along with a heavy body of a man whose face was hidden underneath a creepy doll mask.

" ** _Fucking bastards_**." All eyes turned to the car where a foot was sticking out, cladded in black army boot and dark jeans. They watched as the foot retrieved into the shadows before a loud smacking sound of flesh followed.

Another man flew out, his mask making a painful tearing sound when it got hooked on the edge of the sharp metal of where the door once was. He landed with a painful crack on the ground before a familiar black boot stomped down on his limp body.

From within the darkness of the vehicle, a teenager stepped out.

He was unusually short with raven black hair and piercing silvery eyes. His eyebrows were furrowed as he glared darkly at the man under his feet. He took a deep drag of the cigarette between his lips before tossing the butt on the man under him.

Some bystanders screamed when the fabric of the cloth the man wore caught on flame, but the fire's lifespan was cut short when the teen smeared it out under his boot.

"H-hey…!" The boy that had tried to sneak up on the car spoke up, but was interrupted when a small giggle drew the stunned audiences' eyes to the lump of bounding energy being supported between the teen's left hand and hip.

An elderly woman who was just coming out of the candy store dropped her phone in her shock.

"Again! Again!" The childish voice sang as tiny hands waved excitedly.

"The hell we're doing that again you little shit." The raven haired teen snapped, blowing out a smooth breath of smoke before properly gathering the child into his arm.

As the teen began to walk off, the man who had flew out with the door let out a small groan. He was quickly silenced when the teen delivered a swift kick to the head without even sparing a glance. Many people cringed when they heard the sound of crackling bones.

"Again!" The child pouted stubbornly, blowing up his cheeks as he glowered at the teen carrying him.

"No, we're not doing it again." The teen growled firmly, looking down only to freeze when teary green eyes stared back at him.

"Uh…" The child's face scrunched up as the first droplet of tear broke through, followed by a high pitched whine beginning to escape from his trembling lips.

The teen let out a string of curses as he rushed by the old lady in front the candy store, snatching the bag of candy from her still loosened hold and replacing it with a heavy bill. Just as the child opened his mouth to cry, a lollipop was shoved in.

The change of mood was instant. Tears immediately dried from his eyes as the child sucked at the colourful treat.

"'ank 'ou Levi!" He squealed around the lollipop, looking up with those sparkling gaze of admiration.

"Damn brat." The teen huffed, running a hand through his hair as they entered a dark alleyway just as the sound of sirens came echoing down the street.

oOo

Levi Ackerman did not know how he ended up here.

If anyone were to say he would find a full time career in baby-sitting some rich bastard's spoiled brat a year ago, he would shove a rifle up their ass and pull the trigger.

But here he was, baby-sitting some rich bastard's spoiled brat.

The teen looked down at the small figure curled up against his stomach. Tiny hands clenched onto his black t-shirt as he slept.

Levi put his head back into the pillow and closed his eyes, wondering how his life had gotten to this point.

He remembered the coldness eating him away as blanket of snow covered his body. It was a trap. The stupid informant had set him up. He was one of them—those hypocrites that call themselves the defender of justice. He should have known…he should have seen it coming. He couldn't remember how many times he was shot. All he remembered were the bodies of the law enforcers he had cut down one after another until the blood lost eventually got to him.

That was when he met the Yeagers. They were having a trip in Hokkaido. Eren was the one who had found him slowly withering away in the alley. Since it was early in the morning with the sun hasn't even rise, there was no one else to be seen.

Levi could remember the rage boiling in him when the snot-nosed brat demanded for his attention. He couldn't remember what he spat at the kid, but it had him crying and running back to his parents who were across the street taking pictures of the freshly fallen snow.

It was then when a car came speeding down the road, tires sliding uncontrollably on the thin layer of ice. Levi didn't know what possessed him when he used the last of his strength, leaping out and grabbing the kid.

Everything became a haze after that. There were screams everywhere as his head fell against the cold ground. The last thing he remembered was the high pitched cry of the brat as Levi lost himself to the familiar emptiness.

When Levi opened his eyes, he had expected cold gray walls and iron bars. But instead, he was surprised to find himself tucked under soft sheets in a well-furnished room. That was when he met Grisha Yeager—the founder and head of the world leading company, Titan Inc.

 _"Work for me as my son's caretaker or spend a life-time in jail. The choice is yours._ " Those were literally the first words the arrogant man had told him. Apparently, saving Eren had turned Levi into some sort of hero in the five years old's eyes, and the child **commanded** Levi to spend time with him. And what the spoiled brat wants was apparently what he always get.

Levi had almost laughed right there and then. Perhaps he did, he couldn't really remember. It was the most hilarious thing he had ever heard. The fact that Grisha knew who he was—or rather, who _Rivialle_ was, and still thought he could control him was probably what tipped him over.

It wasn't hard figuring out that Grisha knew who he was. Why else would he want to bring a random thug dying in the alleyway into his family? Grisha Yeager was no angel and Levi knew that all too well. He hadn't wasted his life living in the dark side of society for nothing. He knew who Grisha was. He knew who the man was under the façade he built around himself. He **knew** that the Titan Inc didn't get so big just because he is a good businessman.

And most of all, he knew how.

With one utter of the word _Maria_ , the smugness on the man's face turned sour. Levi could see the realization slowly morphing on the man's face when he realized how Levi wasn't someone the man could manipulate and crush under his feet.

Guards busted into the room, but Levi had already leaped out of the bed, flying towards them with a menacing gleam in his eyes.

It was over in seconds.

Levi stood over Grisha, the barrel of the gun he snatched from the guard pressing between his eyes. The man was trembling and spluttering words, but Levi didn't bother listening. He simply stared at what the most powerful man was reduced to.

It was utterly pathetic.

He thought about killing him. The man had attempted to threaten him after all, and Levi doesn't take threats lightly. He has no qualm on killing the most influential man, nor did he care how many people will be after his head if he did. He was already the most wanted in the underworld. A couple hundred more makes no difference.

But then, Levi remembered the tiredness that had been eating him away for some time now. The boredom he felt when he finishes his target and his growing lack of motivation. It was how he had fallen into that trap in the first place.

So Levi struck a deal.

That day, _Rivialle_ disappeared from the world. All records of the assassin were erased from every existing database. The name became a myth—a tale that would often be told of humanity's strongest assassin.

That day, Levi was born. Levi Ackerman—humanity's strongest _nanny_.

It shouldn't have been that way.

Levi had planned to wait. He had planned to wait until the man erased his existence before killing him. However, the entire process took three days. And in those three days, what stopped Levi in his plan was his charge—Eren Yeager.

For the first in a long time, Levi felt a spark of emotion flaring alive inside him.

He loathed the brat with a burning passion. He couldn't remember how many times he wanted to put a bullet through the kid's tiny skull and watch the brain leak out. The little shit was beyond hope. He was spoiled rotten and demanding. He even had the gall to try and _hit_ him when he didn't do things his way.

…But then Levi realized why.

The way Eren acted wasn't because his parents had loved him to the point where he's been spoiled. It was the opposite. His behaviour was born from neglect.

Despite Grisha's seeming concerns for Eren, he didn't even send a single one of his lackeys to check if the assassin has any ill intention towards the kid. There were only two explanations Levi could come up with.

One, Grisha feared that in doing so, it may anger the assassin and cause Levi to change his mind and finish him off.

Two, Grisha never truly cared for the brat's wellbeing.

Eren had never experienced love. His father simply gave him everything so he wouldn't throw tantrums and shame him for all public to see. He was only a liability and everyone in the household knew. The cooks, the maids, the securities…everyone in the house knew except for Carla Yeager.

Levi didn't know if the woman was simply turning a blind eye because pretending not to know would be easier or if she really couldn't see how their parenting (or the lack of) was ruining their son. Whichever the reason was, she was no better than Grisha, and Levi found his patience for the pair growing thin.

Now thinking back, that might have been when he no longer saw Eren as an arrogant kid, but a victim to neglect like he once was.

It also marked the turning point of both their lives.

 _Buzz_

Levi looked over to the nightstand when he heard the sound of vibration. He reached over, careful not to disturb the bundle attached to him as he picked up his phone. When his eyes landed on the screen however, he frowned and tossed it away.

The phone buzzed for a long time.

When it finally went away, a knock on the door came next. Levi almost growled when a frightened looking maid hesitantly opened the door with a phone held in her hand. She opened her mouth, but quickly clamped it shut when she noticed the sleeping young master.

Heaving out a frustrated sigh, Levi waved her over. The maid hastily complied, trying to keep her footsteps light as she handed over the phone in her hand.

"Yes?" Levi spoke after the maid left, closing the door softly behind her.

 _"Levi."_ A disapproving tone of a woman's voice came from the other end. Levi rolled his eyes. Carla. Of course it's always Carla.

"Mrs. Yeager." Levi deadpanned in a flat voice, showing how little interest he has in talking to her.

 _"Why didn't you pick up the phone?"_ Carla huffed before continuing on, knowing she would never get a proper response for that. _"I saw the news."_

"Which one?" Levi questioned, deciding to humour her.

 _"Which one should I know about?"_ The mother's voice grew stern. _"Is my baby alright?"_

"What's it to you?" Levi asked, perhaps a little defensively. The woman certainly didn't play a motherly role. She has no right to call Eren _hers_.

 _"He is my **son**! Of course I care!"_ Carla exploded, scandalized and offended by the teen's question. It was a reasonable reaction from a mother, but Levi just scoffed. If the woman was truly worried that an attempt of **kidnapping** had happened to her six years old son, then she should drop whatever plans she has with her husband in America and fly back to Germany.

 _"I don't know why my husband is so adamant about allowing you by Eren's side, but I—"_ The mother ranted with Levi barely listening. _"And you smoked!"_

Ah yes…Levi could vaguely remember the picture plastered on the front of the newspaper, taken by some asshole when he stepped out of the van—cigarette in one hand and Eren in his other.

 _"I've told you countless times not to smoke in front of my son!"_

"—evi…?"

 _"Are you listening—"_

Levi shut the phone as he looked down to see green eyes blinking owlish up at him. The teen tossed the phone away, not caring where it landed as he cradled the younger boy.

"Shh…" He whispered soothingly into the boy's ear. "Go back to sleep, Eren."

"Hmm…" Eren moaned tiredly as his eyes fell shut again. "…Goodnight Levi."

A faint, genuine smile tugged on Levi's lips at those words. The child certainly has improved over the year he was here. If it was in the past, it was unthinkable for the little shit to bit anyone a goodnight.

"Ah." Levi's gaze softened. Perhaps a nap right now wouldn't be too bad. "Goodnight, Eren."

* * *

Hello! I hoped everyone has enjoyed this short story! It was something I had in my computer for a long time, so I thought I'd bring it out. It was supposed to be a story way longer than what I have here (maybe even a multi-chapter story), but with the little success I had in my previous Riren story, I don't know how well this will be received.

Please leave a review and tell me what you think. Reviews are what I use to track whether a story is good or not. The more reviews, the more motivated I'll be in working with more Riren stories in the future.

I may or may not write out the full, actual length of this story in the future, but until then, this short little one-shot is complete.


	2. Six Years Old

"Where did he go?"

The thumbing sound of footsteps echoed down the dark corridor.

"He's got to be around here somewhere!" The man leading the group said through gritted teeth as he adjusted his night vision goggle in attempt to see through the shadows in the far distance. The men around him were observing the area cautiously with weapons clutched in their hands—ready to fire at any given moment.

"Sir!" A bearded man suddenly called as everyone turned to see him pointing at something on the ground.

The leader shoved away his men and knelt down to see some black stains on the cracked concrete. He wiped his gloved hand over the sticky fluid, rubbed his fingers together before bringing it up to his nose for a sniff.

The moment he caught that familiar metallic smell, a cruel smirk lifted his lips.

His eyes followed to where the black trail was leading towards and nearly laughed at their prey's stupidity.

Before coming down here, they've studied the blueprint well. They've memorized every nook and corner of this hellhole. The idiot had ran himself into a dead-end. He made a few hand gestures in the air and immediately his men spread out with rifles and guns pointed towards the dark hallway.

"Well, well, well, to think the infamous Rivaille would come to this kind of end!" The leader snickered as his men began to march forward in an organized line—movements completely synchronized. With each step they take, the sound of their footsteps would thunder in the darkness and shook the entire building.

The leader walked behind the line, keeping a safe distance with his men acting as barrier while continuing to throw out words of mockery. "To be betrayed by your own informant! How stupid!"

As the group close in on their destination, their fingers began to tighten on the triggers, ready to pull the moment their target comes into view.

"Look how far you've fallen! The entire underground knows who you are and where you are! There's no place for you in this world anymore!" The man laughed hysterically as though it was the best joke he has ever heard. "Number one hitman?! Don't make me laugh, Rivaille! You don't deserve being called number one! The number one is mine! It was always mine!"

The moment the men took another step, they all froze in shock as they stared at the end of the hallway that had become clear to their vision. There, sitting against the wall, was a man. He wasn't just any man. He was one of their own—a comrade they thought they had lost in the earlier battle.

He was the second-in-command in the operation.

He sat there; eyes wide and unblinking as he stared at them with his mouth wide open. His white shirt was stained by the same dark substance they had been trailing. They could still see some flowing of the wound through their goggles, adding to the tiny puddle under where the man lifelessly sat.

"What's wrong?" The leader asked when his team had stopped. Since he was standing a bit further back, he was still unable to see the end of the hallway.

"Number one?" A husky voice suddenly snorted, sending goose bumps crawling over the man's skin as he quickly whirled around with his gun raised. His men hastily did the same, looking all over the place as they aimed their guns wildly around them—searching for a target.

Out of nowhere, a couple of cylinder objects were dropped right in the center of their formation before an explosion of light overtook the darkness.

The men screamed as they shut their eyes in pain.

No one saw a petite Asian male walking out of the group, dressed the same as everyone else as he removed his night vision goggles, revealing his closed eyes. He pulled out a rectangular package from his pocket and placed it down by his feet.

"You're not even fit for the role if you can't even tell there's an extra member on your own team."

With his eyes still closed, he walked around a corner. Pressing down on the button in his left hand, the entire building shook as explosion blasted through the hallway like a torrent of flames.

The raven haired man ignored the heat of the flames licking at his back as he walked up the stairs, eyes still closed yet somehow able to avoid all the obstacles in his way. It was as though he was able to somehow see with his mind as he moved through the building until he finally reached the surface.

It was when the cold wind brushed again his cheeks did he finally opened his eyes to the starry winter sky.

Rivaille stared at the head of the sun that was already peeking out in the horizon. The light irritates his eyes, but he didn't look away. Despite having lived for so many years, the man realized that he had never properly looked at the sun like this before. Soon, the construction workers will arrive and demolish the building behind him—erasing all traces of the battle that had occurred in the rundown museum.

Feeling warm fluid dripping from the tip of his fingers, he glanced to his shoulder to find that his blood had seeped out of the makeshift bandage again. He clicked his teeth in annoyance, but didn't bother with it.

Right now, his priority is to get out of here first.

The moment he took a step forward, a sense of danger suddenly rushed through him. Without even pausing to think, he ducked behind a car as bullets pierced into the ground of where he once stood. Then another bullet shot right through the outer shell of the car he was hiding behind, hitting right into the fuel tank.

The man wrinkled his nose when he caught the heavy scent of gasoline. This car is completely unusable now.

"Tch…the bastards even called in snipers." He cursed, looking down at his right leg that couldn't evade in time and was pieced through. He ripped off the fabric of his sleeve, using it to quickly bandage his leg before ripping off the side mirror of the car. He held the piece of mirror up, using it to reflect the buildings on the other side of the car. From the location and angle of the bullet holes left on the ground, he was easily able to pinpoint which buildings and levels the snipers were hiding in. And from the amount of bullets that were aimed at him, he'd say there's about five of them.

He looked around and found that the nearest place he could run to was a narrow alleyway. It was just on the other side of the road. While it wasn't far, it was enough to get him killed before he could even get half way there.

He huffed, pulling out a pack of cigarette to found that he only got one left. He snatched it up with his lips and lit it up with his lighter. He took a deep breath before breathing out a puff of white smoke.

Then, with a flick of his fingers, the cigarette flew into the air, creating a smooth ark over the car before landing right into the puddle of gasoline that was leaking out of the fuel tank.

Seven seconds ticked by before the car suddenly blew up before the snipers' eyes.

Shocked by the sight, they can only watch as pieces of the car were blown apart from the force. None of them noticed the car door that was blasted across the street, nor the petite figure that had slipped out from behind door and right into the alley.

Rivaille landed with a pained grunt, but he gathered himself quickly, using the wall as support to pull himself up. The right side of his clothes were burnt off and his skin suffering second-degree burns. However, that matters little to the Asian. His right side was pretty much useless now, so adding some burns wouldn't make much difference.

He limped his way through out the narrow passageway until he found the lid of a sewer. He swore under his breath. Sewers are far from sanitary. Even if all these assassins aren't able to kill him, whatever diseases living down there definitely could. Unfortunately, he doesn't have much choice right now. It was either die here, or later in some garbage dump. He chose the latter. If he was to die, he rather it be from his own stupidity than by someone else's hand. He stuck his finger into the hold of the lid, grimacing at the amount of germs he was getting on his skin as he pulled it open.

With one last look around, Rivaille disappeared into the darkness as the lid fell back into its proper place as though it had never been touched.

As the sun slowly rise into the sky, the citizens of Shiganshina greeted yet another new day.

People walked about the street, completely carefree and oblivious to the battle that had taken place in their city. The workers arrived at the old museum and began the demolish process as scheduled. They put out warning signs all over the street, making sure no one could get near as the building began to crumble, burying the charred bodies of men beneath the earth—never to see the light again.

Even as the night fell once more, the city remained lively and full of lights. A petite man sat in the dark alleyway as he stared at the giant Christmas tree in the distance.

To the happy couples walking about, it was another year of celebration.

To the hitman however, it was just surviving another year.

No…perhaps he wouldn't survive another year.

He lost too much blood…to the point where remaining conscious was all he can do. Not to mention with all these open wounds, he's certain he had at least picked up one or two deadly diseases. He also wasn't wearing much to protect himself from this chilling weather either. The only thing that would provide him the slightest bit of warmth—his lighter—was completely used up navigating through the sewage.

"Wah! It's snowing!" The excited scream caused the raven to turn to the source of the light beyond the shadows where a woman was waving her arms up at the sky with her boyfriend laughing beside her.

The hitman looked up and indeed saw snow fluttering down from the sky. Letting out a small huff, he leaned back against the wall and closed his eyes. For the first time since he could remember, he slept. Not a five minute nap, but a full length sleep that shut away all of his senses and leaving himself vulnerable to the world around him.

As time slowly passed, the night fell into silence once more.

The people were gone, tucked away in the safety of their home as the light of the Christmas tree disappeared, leaving nothing but darkness behind. The only thing left was the tiny little snowflakes, drifting down from the sky as they covered the raven haired male like a thin sheet of blanket.

"Mommy! Daddy!"

A shrilling voice rang next to his ear as the raven haired man's eyebrows twitched.

"Over here! Over here!"

The irritating voice continued, buzzing like an annoying fly as the hitman slowly parted his eyes. His vision was blurry, but he could make out a tiny figure jumping up and down next to him, waving at something in the distance. When he shifted, some of the snow that had gathered on his body fell off.

That caught the tiny thing's attention as he turned, bright green eyes meeting steel grey ones.

Rivaille squinted, trying to focusing his sight until he made out the wide, smiling face of the boy.

"You're pretty!"

Those words caught the man by surprise as his eyebrows twitched. Never in his twenty years of life had anyone ever told him such words before. Usually _pretty_ wouldn't be a description people use on him.

However, the moment was broken when the boy spoke out his next words.

"I found you, so you're mine now!"

"Fuck off." Rivaille hissed weakly. His voice was hoarse and even cracked a little, but it was enough to get the message across.

At first, the boy had a look of disbelieve, obviously his _demands_ have never been turned down before. His cheeks puffed up as he stomped his feet like a cliché pampered brat.

"You're mine!"

"…Are you stupid?"

"You're stupid!" The boy shouted, angry tears brimming around his eyelids. "I'm gonna tell daddy!"

As the boy was turning around, Rivaille caught the sound of car engine approaching from the distance. He looked to the boy who had ran out of the alley, heading towards the other side of the street where a man and woman stood, surrounded by some men in fancy black suit.

"Daddy!" The boy shouted as tall man with rounded glasses turned just as the screeching sound of tires resonated through the air.

The hitman didn't know what possessed him. He didn't even realize he still had this much strength as he flew out of the alley, grabbing the boy by his hoodie with his better hand and flung the brat right into the glasses wearing man.

As the force of the car shattered the left side of his ribcage, Rivaille looked back into his life and found how empty everything has been. Ever since the day he was born, it was nothing but a battle of survival. Every step of his life was paved by the bodies of the people he killed. He never once regretted his choice. He killed because that's what he must do to survive. However, as he had gotten used to killing, he began to feel numb of everything else. There is no thrill or fear when he goes after a target. It was just a job after all—a daily life thing for him.

Day after day, it was always the same. Kill someone, get the money, kill more people, get more money. An endless cycle over and over…

Perhaps this was what he had always been waiting for. Perhaps all this time, he was living just for this moment. The moment where the cycle would finally break, bringing this mundane game to an end. But of course…being the world's number one hitman and the most wanted in the underground society, nothing ever goes Rivaille's way.

He didn't know if he should blame his ridiculously strong vitality or some shitty snot-nosed brat that doesn't understand what _no_ means.

"As you can see, Mr. Rivaille. My son has taken quite a liking to you."

"No shit." Rivaille retorted as he lay in the small, single bed wrapped up in white bandages with multiple IVs injecting all sort of substances into his body. Whatever's going into his veins, Rivaille can be certain that it wasn't anything good judging by how unnaturally numb his body felt. His right hand and leg were in casts with his left limbs chained to the bedpost by handcuffs. He stared at the older man with his right eye—his left bandaged up thanks to the car that slammed into him.

Now that his head is completely clear and his vision no longer blurry, Rivaille recognized exactly who the smug looking man standing before him.

Grisha Yeager.

In the government society, people known him as an accomplished doctor who owns the state's largest hospital.

However, in the underground, he was a scientist running multiple facilities around the world researching and performing illegal human experiments. He was a complete madman, but his skill was something many people in the underground sought after.

"Work for me as my son's caretaker or I could hand you over to the people after your head. The choice is yours."

Of all of Rivaille's life, that must be the most ridiculous demand he had ever heard…and he had heard a lot. He didn't even need to think to know what this man is after. He may say it's for his son, but the look in the man's eyes clearly lust for power.

Power that only Rivaille could give him.

That was what everyone in the underground wanted. With someone as skilful as Rivaille, he became a dangerous entity. Many mafias tried to get him to join their family, but the hitman turned every one of them down. Due to that, he quickly became wanted world-wide. It was simple really. If no one could get him, then they would destroy him before he could turn his guns towards them. They would use him when they could and destroy him the second they get the chance.

That was how he ended up here, because a certain shitty four-eye gave them that _chance_.

And now some shitty four-eye doctor thought he could control him just because he was injured a little bit more than normal.

"What makes you think you're in the position to strike a deal with me?" Rivaille asked as a dangerous glint flashed by his eyes. A veteran would instantly be able to pick up the bloodlust he didn't even bothered to hide, but Grisha Yeager was no veteran. He bet the man never even shot another person before. All he does was conduct experiment on people who can't even fight back.

Then again, if he was as smart as they say, then he wouldn't even think of controlling Rivaille when so many before him—all powerful individuals—had failed.

"You seemed to be misunderstanding your situation, Mr. Rivaille—!"

Without even waiting for the man to finish, Rivaille suddenly bolted forward. The handcuff on his left wrist broke apart through brute strength as he snatched one piece of the broken handcuff and pointed the jagged edge of the metal against the man's delicate throat.

Immediately, guards rushed into the room, all of them armed guns that looked brand new, as though never have been fired before.

Rivaille snorted as he kicked Grisha off his chair before cracking the knuckles of his better hand.

It literally only took him ten seconds.

The guards Grisha had hired might have been pros, but being bodyguards for so long and kept away from action, they have grown sluggish. Rivaille didn't know what kind of life they led before hired by Grisha, but in front of the number one hitman, they were all amateurs.

"So…" Rivaille nudged the barrel of the gun against Grisha's temple. It was a little something he had snatched from one of the guards before throwing him out the window. He sat on the edge of the bed, sucking in a deep breath of the cigarette clasped between his lips before nudging it to the corner of his mouth and breathed out a stream of white smoke.

The man's head was trap under his foot, trembling and spluttering words that he didn't even bother trying to understand. He simply enjoyed the sight of what the charismatic and technically powerful man was reduced to.

Rivaille had seen too much of these kinds of people. These are the people that hides behind others and talk big but when real power stood before them, they could do nothing but coward.

It was utterly pathetic.

He thought about killing him. The man had attempted to threaten him after all, and Rivaille doesn't take threats lightly. He also has no qualm on killing the most influential man. He was already wanted in the underworld, adding in those tax leeching police hardly makes any differences.

But then, Rivaille remembered the tiredness that had been eating him away for some time now. The boredom he felt when he finishes his target and his growing lack of motivation. That was how he had fallen into that trap in the first place.

"…Let's make a deal." Rivaille smirked. It was just a spur of the moment, but Rivaille didn't think too deeply into it. After all, when he gets bored, he can just massacre everyone and leave. "I'll take on that babysitting position of that bratty kid of yours. For that and in exchange for your life, you're going to do me a little favour."

"I-I'll do anything…!" The man whimpered when Rivaille grinded his foot against his head, pulling some hair out of its roots and further pushing the man's face into the marble tile.

"Put up a notice for all the underground to see. Tell them Rivaille has died under the hands of your men. It shouldn't be too hard for you to get me a doppelganger and implant my DNA into the body right?"

The man instinctively tried to nod, but when he found that he couldn't because of Rivaille's foot, he spluttered his words out. "Y-yes, yes!"

"Good." Rivaille removed his foot. His lips lifted in a faint smirk as he slowly rolled out a tiny capsule hidden under his tongue. The moment Grisha tried to get up, a pain prickled the side of his neck. He raised his hand only to find something small and cold sticking out of his skin.

"W-wha—?!"

"You won't die, relax." Rivaille huffed at the paleness of the man's face. Now that he took a closer look at him, the man already seemed to have aged ten years compared to when the hitman first saw him after waking up.

"That's just a special type of bacteria created by a certain _acquaintance,_ " Rivaille bit out the word there, "of mine. They're perfectly harmless until mating season, which happens early spring—around March. The types I've given you are all females. I have the males. Get the picture now?"

As pathetic as Grisha is, he is a smart man and was immediately able to put the pieces of Rivaille's words together. The man gritted his teeth as he glared at Rivaille with both hate and fear as he took in the information. As a scientist, he had never heard of such bacteria before. It has to be a bluff—

"Whether it's a bluff or not, you'll find out when the time comes."

"What do you want? I said I will do as you—"

"It's just a little precautious. Don't worry. As long as you don't plan on turning against me, I have no reason to kill you. Who knows? Maybe we'll get along in the future."

With that, Grisha's fate has been sealed as the dark cackle of the devil rang next to his ears.

A week later, the name _Rivialle_ forever disappeared from the underground.

Humanity's strongest hitman has been killed. Many large organizations secretly let out a breath they had been holding for years. Rivaille's name that has been sitting on the top of the chart was finally removed and replaced by another. With the biggest threat to all under-grounders gone, their society continued to function as normal.

Within a month, no one bothered remembering the once greatest hitman anymore. His name faded away, joining all those other names that were lost in the darkness.

At the same moment Rivaille's name vanished, a new name was born.

Levi Ackerman—humanity's strongest _nanny_.

"No!" A high, squeaky voice echoed down the hallway, followed by the sound of shattering glass.

As Levi strolled down the long hallway, he could hear the maids of the manor gushing over the brat, using those disgustingly _sweet_ voices in attempt to calm the child.

With a click of his tongue, Levi raised a foot, ignoring the butler screaming behind him as he kicked the door off of its hinges. All at once, the noises in the dining room died away. When the maids saw Levi approaching, they quickly backed away. While they had never interacted with the newbie worker, just his aura was enough to make them tremble in fear.

They couldn't understand why the master of the manor would hire a guy like this to look after their young master. More than that, they couldn't understand why this violent man was given rights over all the servants in the house.

"What's going on here?" Levi asked, looking down at the shattered plate of food before turning to the older and more experienced looking maid.

The old lady jumped when his eyes landed on her, but quickly explained nonetheless.

"T-the young master wouldn't eat his dinner…" The old lady shuddered when Levi's glare grew cold.

"Why?"

The elderly maid was stunned by his question. Her eyes darted around as she thought over everything that had happened before remembering the root of the problem. "This a-afternoon…the young master wanted to eat candy so we—"

"I'm not hungry!" Eren Yeager —the spoiled brat of Grisha—declared. "I'm going to play!"

The boy hopped out of his chair. When a butler came up in attempt to reason with him, he was rewarded by a kick in the shin.

Levi narrowed his eyes.

With two wide strides, he crossed the distance between them. He picked up the boy by the back of his collar and before anyone could react, he drilled his knee into the kid's stomach.

Immediately, stomach fluid along with the shit the brat had eaten from the afternoon gushed out of his mouth along with tears and snots.

The maids and butlers were shouting as they tried to approach them, but were easily stopped by a single glare from the ex-hitman.

Levi dropped the kid, waiting for him to finish emptying his stomach before picking the boy up and dropping him back into his chair.

"Someone get some food and clean this disgusting shit up."

Levi pulled out a chair beside Eren and sat down; ignoring the way the boy was pitifully curling into himself, no doubt still feeling the pain.

Time slowly ticked by.

By the time Eren's hiccups died away, a maid finally returned with a plate of food. Levi frowned at time it took for that girl to get food. Looks like it's not just the brat he'll have to re-educate.

"Get over here." Levi frowned when he saw the girl still standing by the doorway.

At first the girl was hesitant, but when Levi's brows began to furrow in impatience, she quickly ran over, almost tripping a couple of time in her haste.

"Took you long enough." Levi snatched the plate over as the maid paled.

"Um, t-that's—" Levi glared at her, causing her to shrink back and shook her head, indicating that there's nothing.

Even without the maid speaking, Levi knew what the issue was.

The food on this plate obviously looked plainer and more simplified compared to the one on the floor. It wasn't hard for Levi to guess that this is the servant's food and that Eren's proportion are all gone because the brat decided his food fits the floor more.

"Your stomach should be empty now right? Eat." Levi slid the plate over to the kid. He didn't raise his voice, but that just made it ten times scarier as the child shivered under his presence. Large, pearly tears were rolling down his face, but he didn't dare to cry out loud. He was even trying to hide his sniffs, scared that if he makes even the slightest noise he'll get beaten again.

Levi felt something pricked his heart at the sight. He frowned as he looked away from the boy, trying to figure out what came over him. It was a weird feeling—something completely new and unknown that intrigued Levi.

"Ugh…uh…" Hearing pained moans, Levi looked back to the kid to see him struggling to swallow the food in his mouth.

At first, Levi wondered if he had hit the brat's stomach too hard. He was certain he had held back. However, when he looked closer, he realized it was just the kid was trying to shove too much down his throat at once.

"Are you stupid?" Levi growled as he pulled the kid's hands away from his mouth and gave a sharp pat against his back, forcing him to spit his food back into his plate.

"D-don't huwrt me!" The kid cried as Levi's brows twitched again. He was tempted to whack the kid over his head, but decided against it at the last moment. He wrinkled his nose at the mush all over the plate. Swallowing his disgust, he grabbed a fork and stabbed it into a piece of smaller meat and held it up to the kid's mouth.

"Take small bites or you'll choke yourself." Levi said coldly.

Not daring to defy him after what happened, the child quickly leaned forward and bit into the soggy meat. He chewed quickly at first, but when he saw Levi glare at him, he slowed down. He chewed and chewed until all the flavour in the meat is gone. He swallowed it before opening his eyes to see a piece of veggie held in front of him. It was a carrot, something he hated, but didn't dare to voice it out.

Levi watched as the kid ate the carrot with a pained look on his face. Once the kid finally swallowed, he held the fork over to the kid.

"You can eat by yourself, can't you?"

The brat quickly took the fork from him. It was then that Levi realized how small that hand is. How old was this kid again? Six? When Levi thought about it, it was right around six that he made his first kill.

Time slowly ticked by as Levi watched the boy eat. He could tell that the kid's already full and couldn't eat anymore, but the brat didn't dare to voice it out. He just keep picking at the remaining food, sweat rolling down his face and tears threatening to fall again.

With a sigh, Levi stood up. It was 10:30, about time for little brats to go to bed anyways.

"Come on, you're going to sleep."

Eren perked up at his words. In the past, the kid would have thrown a tantrum about not wanting to go to bed. Now, he couldn't be more eager. Anything to get away from the torture of stuffing himself.

However, when the boy tried to get up, he cried out at the sharp pain coming from his stomach. He held onto his tummy and tears were streaming down all over again.

"Tch." Levi reached a hand out to the kid, only to notice how filthy the brat is. His shirt was filled with bits of food and sauce…as well as some of his puke. Grimacing, Levi grabbed the back of the boy's shirt and easily tore it off him.

"L-Levi-san!" The servants around him gasped before Levi yanked off the brat's pants as well. He then looked around the servant before spotting a butler who was holding a clean change of table cloth.

"Hey you, get over here." The butler was startled at being called. He hesitated just like the other maid, but when he saw the look Levi was giving him, he all but scrambled over.

Levi snatched the table cloth out of his hands, mentally reminding himself to do something about these useless workers. When Levi turned back to the naked kid, his gaze stopped at that bruising stomach. The man frowned. He had definitely held his strength back when he kicked the spoiled bastard. For it to still bruise like that…it was definitely out of his calculation.

The kid's body was weaker than he had expected…but then again, Levi never dealt with kids before so he didn't know what to expect. Giving that darkened patch one last look, the raven haired man threw the white sheet over the boy, wrapping him up like a burrito. He was going to toss the boy over his shoulder like a sack of potatoes when he remembered the kid's injury that he had given. With a sigh, he gathered the kid into his arms and began to head towards the unnecessarily large bathroom upstairs.

"You there. Call a doctor and tell him to wait in the brat's room." Levi ordered when he passed by the head butler who looked like he was close to fainting from the over-excitement this one night has brought him. Levi frowned, lifting the priority of dealing with the workers even higher.

The walk down the hallway was silent.

At least, that's what it began with until he started to hear small sniffs coming from the bundle against his chest. He looked down to see the boy trying to use the blanket to muffle his noise as he cried.

"What now?" Levi asked, irritated that the brat cries so often.

The boy froze at Levi's voice before he quickly shook his head, not daring to say anything as he buried further into his arms. The boy's action made no sense to the scowling man. After all, if the kid is crying because he's scared of him, why would he try to get even closer to him and not the opposite? Levi didn't know the answer and he has no interest finding out. He was just thankful that the kid was smart enough to cry into the table cloth instead of his shirt. Otherwise it wouldn't be just a sore stomach the brat would be crawling away with.

After some thorough bathing—plus some screams and more crying—Levi brought Eren to his room where a doctor and a butler waited.

The doctor was around thirty years old with short brown hair and a plain face that could blend into any crowd. When the two men saw their young master whose eyes were puffy with tears and skin raw from all the scrubbing, they both freaked out.

Needless to say, Eren didn't dare to skip a meal since then…and may have also learned how to properly wash himself without anyone's help.

* * *

 _Author's note_

* * *

Here it is! The official chapter one of the story! I can't believe it has been two years since I first posted this one-shot! I am really happy with the responses I got so I decided to make this a multi-chapter story! Thank you all so much for your supports and I apologize for taking so long!

While I say multi-chapter, there's not going to be any plot. It'll just be random, unrelated chapters of the daily things in Levi's and Eren's life. The reason for that is because I'm not confident in my ability to keep a story updated, so please look at this as just a bunch of one shots together instead of a story.

The chapter names will go by Eren's age to show when the event has occurred. Sometimes I might jump back and forth from future to past, depending on what I come up with.

Finally, I apologize if the abusive behaviour to kid Eren makes anyone uncomfortable. I promise this will be the only chapter that'll have child abuse! I feel bad writing it but it's necessary for the story! Due to the environment Levi grew up in, it's only logical that he doesn't know any other way to teach someone other than to beat it into them. He'll definitely change his ways later on and becomes a real family with Eren.

This story is aiming for light hearted comedy and fluff! There's **not** gonna be any dark stuffs like angst, self-harm, character deaths, etc!

Thank you all for reading! I hope everyone has enjoyed this chapter! Please leave a review if you have the time and tell me what you think!


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